1. Field of the Invention
The present invention relates to an optical waveguide having fiber guide grooves in which optical fibers are inserted, and to an optical module including the optical waveguide. More particularly, the present invention relates to an improvement in spreadability of adhesive with which optical fibers are fixed to an optical waveguide.
2. Description of the Related Art
Information transmission has hitherto been performed between boards and between chips in electronic apparatuses by means of electric signals. In order to realize information transmission with a larger capacity at a higher speed, optical interconnection techniques have attracted attention. As one optical interconnection technique, an optical module of a waveguide type using a planar optical waveguide has been proposed.
Japanese Patent No. 2893093 proposes an optical module of such a waveguide type. In this optical module, a planer optical waveguide is provided on a silicon substrate, and the silicon substrate has a fiber guide groove in which an optical fiber is inserted so as to be optically coupled to the optical waveguide.
In contrast, Japanese Unexamined Patent Application Publication No. 2007-178852 proposes an optical waveguide formed of a polymeric material and including fiber guide grooves. This structure is less expensive than the above-described structure in which the fiber guide groove is provided in the silicon substrate.
For example, such an optical waveguide formed of a polymeric material is mounted together with an optical element on a silicon substrate so as to constitute an optical module.
When a sudden thermal shock is given to the optical module including the optical waveguide formed of a polymeric material, the optical waveguide and the optical element are misaligned and the optical waveguide is cracked because the optical waveguide formed of an organic material and the silicon substrate formed of an inorganic metal have different coefficients of thermal expansion.
Accordingly, in a technique disclosed in Japanese Unexamined Patent Application Publication No. 2007-072007, an optical waveguide formed of a polymeric material and optical fibers inserted in fiber guide grooves provided in the optical waveguide can be fixed together by a fixing member formed of a transparent inorganic material, such as glass, which has a low coefficient of thermal expansion and a high heat resistance.